1. Field of the Invention
The present invention relates to a road name displaying method and a navigation device. More particularly, the present invention relates to a method for displaying a road name in a navigation device operable to guide a vehicle according to a searched guidance route and to display the road name of a next road to be traveled, and to the navigation device.
2. Description of the Related Art
Generally, there are two types of navigation device, namely, a map-guidance type and an arrow-guidance type. The map-guidance type navigation device is designed to draw a map and a guidance route on a display screen, while superimposing a vehicle position mark indicating a present vehicle position at a predetermined position on the map. This navigation device displays the vehicle position mark such that it is relatively moved along the guidance route on the display screen, in accordance with the movement of the vehicle.
On the other hand, the arrow-guidance type navigation device, as shown in FIG. 7, is designed to draw a guidance route and roads crossing the guidance route in a very simple way, and to designate a guidance traveling direction for the vehicle at each intersection by an arrow mark. Further, this navigation device displays on respective display parts 1 to 6, the following information: (1) the name of a road on which the vehicle is traveling; (2) the name of a next road to be traveled beyond a next intersection; (3) a distance to the intersection; (4) a graph illustrating the remaining distance to the intersection; (5) a direction from the present vehicle position to a destination, and a distance to the destination; and (6) an expected time of arrival at the destination. Also, it may guide the recommended traveling direction of the vehicle at the intersection by voice.
In the conventional arrow-guidance type navigation device, when the next road to be traveled beyond the next intersection is not geographically named, on the display part 2 is displayed a message xe2x80x9cUNNAMED ROADxe2x80x9d as an approaching road name. The example of FIG. 7 illustrates that in a case where the next road to be traveled beyond the intersection C11 or C21 has not been named, the message xe2x80x9cUNNAMED ROADxe2x80x9d is displayed as the approaching road name on an arrow-guidance-screen AG11 or AG21 regarding the intersection C11 or C21. In a case where the next road to be traveled beyond the intersection C31 is geographically named xe2x80x9cB ST(Street)xe2x80x9d, the message xe2x80x9cB STxe2x80x9d is displayed on an arrow-guidance-screen AG 31 as shown in FIG. 7.
Moreover, as illustrated in FIG. 8, the conventional arrow-guidance type navigation device displays a message xe2x80x9cRAMPxe2x80x9d as the approaching road name on the display part 2, if the next road to be approached is a ramp. Thus, in FIG. 8, after following the driving direction at each of the intersections C12 (an entrance to a highway), C22, and C32, the vehicle enters the corresponding ramp, resulting in the disadvantage that the message xe2x80x9cRAMPxe2x80x9d is constantly displayed as the approaching road name on each of the arrow-guidance-screens AG12, AG22, and AG32 for the intersections C12, C22, and C32.
As described above, even though the road to be traveled beyond the intersection is unnamed, the display of only the message xe2x80x9cUNNAMED ROADxe2x80x9d is inconvenient to a user. Also, even if the road to be approached is the ramp, the display of only the message xe2x80x9cRAMPxe2x80x9d is similarly inconvenient to the user.
The present invention has been accomplished in view of the above-mentioned technical background, and it is an object of the present invention to provide a road name displaying method that permits the normal and convenient display of the road name to the user, even though the next road to be traveled or approached is unnamed, and to provide a navigation device using the road name displaying method.
It is another object of the present invention to provide a road name displaying method that permits the normal and convenient display of the road name to the user, even though the next road to be traveled or approached is a ramp, and to provide a navigation device using the road name displaying method.
To solve the foregoing problems, according to a first aspect of the present invention, there is provided a navigation device operable to guide a vehicle in compliance with a searched guidance route and to display the road name of a next road to be traveled, wherein, in a case where the next road to be traveled is not named, the navigation device determines a first available road having a road name from the roads included in the guidance route beyond the next road, and displays the road name of the determined road. This permits the normal and convenient display of the road name to the user, even though the next road to be traveled is unnamed.
According to a second aspect of the present invention, there is provided a navigation device operable to guide a vehicle in compliance with a searched guidance route and to display the road name of a next road to be traveled, wherein, in a case where the next road to be traveled is a ramp, the navigation device determines a road past the ramp that is connected to the ramp and included in the guidance route, and displays the road name of the determined road. This permits the normal and convenient display of the road name to the user, even though the next road to be traveled is a ramp.